battery knowledge
 

I recently learned that, without modification, there is no possibility of ever FULLY charging the battery BY DRIVING.
Thus our batteries are not lasting as long as they might, especially if the charge gets low e.g. if allowed to stand for a few days.

This is probably because software control is aimed at reducing alternator load to produce better fuel economy figures in government testing.

In our cars, if the battery is low, on startup "it will deliver about 20A at 14.45V for a minute, then reduce to about 4A for a couple of minutes then taper off to NIL
with the voltage across the battery falling below 13V."

In prior decades the alternator would supply a constant 14.4V.
If anyone knows how to change our software to make that happen then let us know.

Meanwhile, using a charger regularly to top up the battery is a solution.

Are you having electrical issues? Battery discharging? No start or slow start condition?

Well, I don't know about all of that, all I know is that the alternator in my 2013 FR-S produced enough electricity to run the car and has kept the battery charged for the past 5 years, with many short trips.


:iono:


humfrz

Just changed my 2013 original battery last month. Got a solid 5 years of daily driving everyday.
So I don't know what you are smoking but pass that stuff over here.

If you don't have any problems, you are way overthinking this.

I used to commute one mile, with the stereo on, the lights on, and the defrost going too. This is not long enough to charge my car. And after a week of quick 1 mile trips, my car would die.


Now that I drive 50+ miles each way, my battery stays FULLY charged. I have tested its voltage; it's good to go now.


I have also upgraded from, IMO, the crappy Panasonic battery.

I know less than the battery engineers at work, and probably much less than the battery engineers at Toyobaru.

I ran my OE flat two or three times (dome light left on, trunk open) and it lasted just shy of 5 years, the Panasonic is a tank as long as you don't drive too little. 1 year on a lightweight PC680 battery with no issues on a <5 mile commute (~15 minutes in traffic).

So what's the problem again?

People don't think chemisty be like it is, but it do.

I disagree.

:popcorn:


humfrz

Service manual says Alternator voltage output should be between 11-14v.

What if I do drive very little and also ran it flat(trunk open) a couple times? Should I then do a trickle charge for a couple hours every couple months in that case?

Re-read the part where I'm not a battery engineer
:bonk:

The new systems are smart.
The old voltage regulators were slow to react and were not very accurate.
After starting you should get 14.2 or 14.4 depending on where you measure. that is full charge voltage the amps depend on the state of the battery. After the battery approaches full charge the voltage will drop to about 13.6, this is a maintain voltage for the battery. If it stayed at 14.4 it would over charge and convert the water in electrolyte to gas. A comin problem with old cars. The new cars often have a voltage and charge sensor connected to the battery terminal.
I might suggest that you check the battery terminals to make sure there is a good connection, then do a load test on the battery. A lead acid battery that has been fully discharged will have a loss of load capacity each time it is fully discharged. (The exception are deep cycle type.)
It is possible you have a bad regulator. Excluding the sensor type most are "one wire" type and are built into the alternator.
Even if you put a battery on a new smart charger, out of the car, you will see the same kind of a voltage drop.

All this ^

There is zero need to have 14 volts all the time.Old cars just did it because they were dumb and didn't know any better.

If you can design a chemical energy storage device not subject to degredation you'd be a wealthy man.

I would think the ECU would put up a CEL if the voltage isn't within spec?

If you're such a hotshot battery engineer then why during a discharge of electricity does the chemical on the anode release electrons to the negative terminal and ions in the electrolyte through an oxidation reaction?

Well I have learned some more from you people. I just read the info. in Silicon Chip magazine July 2018 page 12 and thought I should post it, but it sounds as if it was not quite the full story. I am not having a problem other than I got only 4 years from the o.e. battery and our car does just stand for up to a week fairly often.

I have one running around here - she is my 2 year old granddaughter - :eyebulge:


humfrz

I only got 3 years out of my OE battery. Parked it for 2 weeks in the winter, came back to 2 volts across terminals. Would not hold a charge after that no matter how much I tried charging with various methods. It would actually hit 13-14 volts, then slowly drain to 10 after the charge leads removed with absolutely no reserve capacity.

They were so dumb that sometimes you could rap the voltage regulator up side the case with a screwdriver handle and it would start working again.


humfrz

Unless things have changed with Panasonic batteries the last 5-6 years, then I'm not aware of it. My Panasonic in my xA lasted 9.5 years, and finally died towards the end of 2016. At that point, I had about 85k miles on the car. About a year previous to replacing it (got a Optima Red top), I had left on the dome light over one late Fall night (so it was on a solid 12 hours), so that drastically drained the battery. I was able to revive it(charged it over 8-10 hours), and it lasted about 12-14 months past that point.

Yea things have changed, the panasonic battery in our cars is trash, and is under powered for the car honestly. Well known to become a problem on the BR-Zs with more active electronics when the car is off at 4 years. On my FR-S I've already replaced it, on my friends 2014 it got replaced after only 3 years. It's simply not the right size for our cars and the quality is crap.

Still on my original battery. I have, mostly through my past experience servicing home electronics, become a die hard fan of Panasonic's approach to design and documentation, no matter what their product. I was truly excited to see the label on the battery. When the time comes, I'll replace it with the same.

Gotcha.

OK, the other point I wanted to make was (it's common knowledge, but in case others didn't know) : batteries lifespan decreases when outside ambient temperatures are at their extremes (below freezing , and above say 90 F). If you live where the temps are more temperate ( 40-80 degrees night/day year round) you're good to go. If you live where it snows , or desert (90+ degrees) several days per year then your battery will live a short life.

I'd think (believe) colder temperatures do more damage to batteries, then hotter temps (both aren't good). This winter, when temps are going to be under 32 degrees at night for 7-10 straight days, I'm going to give my battery a trickle charge for 8-12 hours at least once maybe twice this winter

I got rid of the OE one mostly for piece of mind. Running extra electronics and wires here and there. Cold crank being a tiny bit longer. I figured it wouldn't hurt to bump up the juices. I think the cold crank helped and it helped reduce the ignition coil code for me. I got the code a lot less frequently.